The present invention relates generally to the manufacture of electromechanical machines, such as electric motors. More particularly, the invention relates to an expanding arbor used in manufacturing a laminated stator or armature for use in such a machine.
Expanding arbors are often used in the manufacture of lamination assemblies. For example, an expanding arbor may be employed to hold a stack of individual laminas that are to be connected together by welding or cleating. A laminated stator formed in this manner has a cylindrical central opening through which the rotor of the electromechanical machine extends. The lamina includes a plurality of individual teeth defining slots that carry the machine windings. It will be appreciated that each individual lamina is similarly provided with a central opening and these radially extending slots.
In order to produce a stator lamination assembly, the laminas must be aligned and stacked to the proper height. To achieve this result, the individual laminas are stacked on the arbor, which has a vertical core that passes through the central openings of the stacked laminas. In operation, the vertical core expands radially against the inner circumference of the individual laminas. As a result, the central openings of all of the laminas stacked on the arbor are concentrically aligned.
It also is necessary to radially align all of the slots of the individual laminas before the lamina stack can be connected together to form the lamination assembly. This is typically accomplished using a plurality of hardened fixtures known as alignment keys. The keys are symmetrically spaced about the vertical core member so that each key engages a corresponding slot gap in each of the laminas. Typically, four to six keys are used in order achieve desired quality levels of the finished product. The keys collectively function to force the slots of each lamina into radial alignment with the slots of the other laminas. Each key is sized and configured for the slot of the stator being stacked on the arbor. Different stators have varying numbers of slots, and slots with different gaps. Each such gap requires a correspondingly sized key.
Setting up expanding arbors of the prior art for different lamination sizes and types is time consuming. Before the laminas of a new stator are stacked onto the arbor, the vertical core member must be equipped with the keys required for the particular slot gap of that stator. It may take approximately twelve to fifteen minutes to set up an arbor with the new alignment keys. This set-up time is inefficient, and thus impacts the productivity of the manufacturing facility.